Breathing circuit systems and devices

ABSTRACT

A filler device includes a distal housing comprising a distal inner port and a distal outer port; a proximal housing comprising a proximal inner port and a proximal outer port, the proximal housing being sealingly affixed to the distal housing to form an inspiratory pathway between the distal inner port and the proximal inner port and to form an expiratory pathway between the distal outer port and the proximal outer port that is fluidly sealed from the inspiratory pathway, the inspiratory pathway being laterally adjacent the expiratory pathway; and a first filter in the inspiratory pathway or in the expiratory pathway to filter gases flowing through the inspiratory pathway or the expiratory pathway.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/770,455, filed Apr. 23, 2018, which is a § 371 application ofInternational Application No. PCT/US2016/058528, filed Oct. 24, 2016,which claims the benefit of U.S. Provisional Patent Application No.62/300,758, filed Feb. 26, 2016, and of U.S. Provisional PatentApplication No. 62/245,987, filed Oct. 24, 2015; the aforementionedpatent applications are incorporated herein by reference in theirentirety.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to medical devices, and moreparticularly, to breathing circuits and filters structured to circulateinspiratory gases to, and expiratory gases from, a patient.

BACKGROUND

Breathing circuits convey gases from a source of the gases to a patient.The gases generally comprise air and anesthetic drugs. The anestheticdrugs are dispensed by the source of the gases in different amountsbefore, during, and after a medical procedure. Examples of sources ofgases include anaesthesia machines and ventilators, typically found inoperating rooms in hospitals. These machines typically recycle exhaledgases and self-calibrate based on the resistance to gas flow presentedby the breathing circuit or a portion thereof. Breathing circuits areprovided by breathing circuit systems.

Anaesthetic gases intended for the patient may leak to the environmentthrough joints and, if leaks occur, the patient will not receive thedesired intervention. Additionally, the leaked anaesthetic gases couldbe breathed by medical practitioners, with potentially negativeoutcomes. Furthermore, loss of anaesthetic gases increases treatmentcosts.

Improved breathing circuits are desirable to overcome the aforementionedproblems with current breathing circuits.

The background to the disclosure is described herein, includingreference to documents, acts, materials, devices, articles and the like,to explain the context of the present invention. This is not to be takenas an admission or a suggestion that any of the material referred to waspublished, known or part of the common general knowledge in the art towhich the present invention pertains, in the United States or in anyother country, as at the priority date of any of the claims.

SUMMARY OF DISCLOSED EMBODIMENTS

Filter devices and breathing circuit devices comprising filter devicesare described disclosed. In some embodiments, a filter device includes adistal housing comprising a distal inner port and a distal outer port; aproximal housing comprising a proximal inner port and a proximal outerport, the proximal housing being sealingly affixed to the distal housingto form an inner pathway between the distal inner port and the proximalinner port and to form an expiratory pathway between the distal outerport and the proximal outer port that is fluidly sealed from the innerpathway, the inner pathway being laterally adjacent the expiratorypathway; and a first filter in the inner pathway or in the expiratorypathway to filter gases flowing through the inner pathway or theexpiratory pathway.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of this invention, and the manner of attaining them, willbecome more apparent and the invention itself will be better understoodby reference to the following description of embodiments of theinvention taken in conjunction with the accompanying drawings, wherein:

FIGS. 1 and 2 are perspective and schematic illustrations, respectively,of a breathing circuit system forming a breathing circuit;

FIG. 3 is a section perspective view illustration of an embodiment of afilter device;

FIG. 4 is a perspective view illustration of the filter device of FIG. 3;

FIG. 5 is a perspective view illustration of a component of the filterdevice of FIG. 3 ;

FIG. 6 is a section perspective view illustration of another embodimentof a filter device;

FIG. 7 is an elevation view illustration of an embodiment of a devicecomprising the filter device of FIG. 3 integrated with a coaxialbreathing tube;

FIG. 8 is an elevation view illustration of an embodiment of a devicecomprising the filter device of FIG. 6 integrated with a unilimbbreathing tube;

FIG. 9 is a section view illustration of yet another embodiment of afilter device;

FIG. 10 is an expanded section view illustration of a joint of thefilter device of FIG. 9 ;

FIG. 11 is a perspective view illustration of an embodiment of a testplug;

FIG. 12 is a perspective view illustration of the test plug of FIG. 11blocking an inner port of a unilimb breathing tube;

FIG. 13 is a perspective view illustration of the test plug of FIG. 11blocking an outer port of the unilimb breathing tube;

FIGS. 14 to 16 are section elevation view illustrations of embodimentsof a unilimb breathing tube; and

FIG. 17 is a section elevation view illustration of an embodiment of adistal connector of a unilimb breathing tube.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings representembodiments of the present invention, the drawings are not necessarilyto scale and certain features may be exaggerated to better illustrateand explain the embodiments.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

For the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and described below. The disclosed embodiments are notintended to be exhaustive or limit the invention to the precise formdisclosed in the following detailed description. Rather, the embodimentsare chosen and described so that others skilled in the art may utilizetheir teachings. It will be understood that no limitation of the scopeof the invention is thereby intended. The invention includes anyalterations and further modifications in the illustrated devices anddescribed methods and further applications of the principles of theinvention which would normally occur to one skilled in the art to whichthe invention relates.

Filter devices and breathing circuit devices comprising filter devicesare described below. Ventilators may perform leakage tests and performself-calibration based on the resistance to gas flow presented by thebreathing circuit. The distal end of the breathing circuit may besuitably plugged to permit separate testing of the inspiratory andexpiratory tubes. As technology advances, ventilators may be able todetect leakage of smaller amounts of gases, even smaller than what maypresent a concern from a medical or environmental perspective. Yet ifleakage is detected, the breathing circuit may not be used or additionallabor may be necessary to determine the cause of the leakage.

Breathing circuits and filter devices are disclosed below thatadvantageously seal inspiratory and expiratory pathways from each otherand from the environment, overcoming the aforementioned problems.Additionally the filter devices may permit size and cost reductions dueto their configurations and integration with other components of thebreathing circuit.

In some embodiments, a filter device includes a distal housingcomprising a distal inner port and a distal outer port; a proximalhousing comprising a proximal inner port and a proximal outer port, theproximal housing being sealingly affixed to the distal housing to forman inner pathway between the distal inner port and the proximal innerport and to form an expiratory pathway between the distal outer port andthe proximal outer port that is fluidly sealed from the inner pathway,the inner pathway being laterally adjacent the expiratory pathway; and afirst filter in the inner pathway or in the expiratory pathway to filtergases flowing through the inner pathway or the expiratory pathway.

As used herein, “unilimb breathing tube” refers to a device having aninner tube inside an outer tube. The inner tube is generally aninspiratory gas tube and the outer tube is generally an expiratory gastube. Unilimb breathing tubes may also be referred to as coaxialbreathing tubes, whether or not the inspiratory and expiratory tubes areconcentric. In one embodiment, the inspiratory and expiratory tubes areconcentric at their proximal ends and not at their distal ends. Inanother embodiment, the inspiratory and expiratory tubes are concentricat their proximal ends and also at their distal ends. The unilimbbreathing tube is a component of a breathing circuit system formed bythe ventilator, the unilimb breathing tube, and a gas delivery device.

As used herein, a “gas delivery device” is a device used to exchangegases between the breathing tube and the patient. Example gas deliverydevices include face masks and airway devices including laryngeal tubes,endotracheal tubes, and laryngeal masks. An example face mask isdescribed in commonly owned U.S. Pat. No. 7,753,051, titled “Face MaskStrap System,” issued on Jul. 13, 2010, which is incorporated herein byreference. Another example gas delivery device is described in commonlyowned U.S. Pat. No. 7,201,168, titled “Non-tracheal Ventilation Tube,”issued on Apr. 10, 2007, which is incorporated herein by reference.

An embodiment of a breathing circuit system 10 will now be describedwith reference to FIGS. 1 and 2 . Breathing circuit system 10 forms abreathing circuit shown in FIG. 2 . As shown in FIG. 1 , breathingcircuit system 10 comprises a ventilator 12 having an inspiratory gasoutlet port 14 and an expiratory gas inlet port 16. Inspiratory gasoutlet port 14 is connected to a manifold 18 which has inspiratory gasand expiratory gas lumens. The inspiratory gas lumen has a proximal portthat is offset by about 90 degrees from a proximal port of theexpiratory gas lumen. The inspiratory gas lumen and the expiratory gaslumen have coaxial distal ports. As used herein, proximal end refers tothe machine end of the breathing circuit and distal end refers to thepatient end. A tube 20, which has a single lumen, connects expiratorygas inlet port 16 to the proximal expiratory gas port of manifold 18.The coaxial distal ports of manifold 18 are fluidly coupled to a unilimbbreathing tube 22. Unilimb breathing tube 22 includes a distal connectorthat is connected to a gas delivery device 24. A face mask is shown asan example of a gas delivery device 24. Unilimb breathing tube 22includes an inner, or inspiratory, tube inside an outer, or expiratory,tube. Both tubes are connected to proximal and distal connectors or to afilter device and the distal connector. Linear expansion of unilimbbreathing tube 22 causes both tubes to expand.

As shown in FIG. 2 , a breathing circuit comprises ventilator 12, whichmay include a carbon dioxide absorber 28 intermediate an inspiratory gaspathway 30 and an expiratory gas pathway 40. Fresh and recycled gasesare supplied via inspiratory gas pathway 30 to the lungs 38 of thepatient. Expired gases pass through expiratory gas pathway 40 to returnto ventilator 12, where they may be scrubbed and recycled. Inspiratorygas pathway 30 includes pathways through inspiratory gas outlet port 14,manifold 18, and an inner tube 32 of unilimb breathing tube 22.Expiratory gas pathway 40 includes pathways through an outer tube 34 ofunilimb breathing tube 22, manifold 18, and expiratory gas inlet port16. Space at the distal end of unilimb breathing tube 22 and within gasdelivery device 24, where inspired gases and expired gases are notseparated and can mix, is referred to as “deadspace”. Ventilators candeliver tidal volumes in pediatric unilimb breathing tubes that may besmaller than the deadspace. Additional components may also be includedto connect unilimb breathing tube 22 and gas delivery device 24, such aselbows and swivel connectors. These devices change the orientation ofgas delivery device 24 relative to unilimb breathing tube 22.

Generally, breathing tubes include single and dual limb devices. In duallimb devices, the inspiratory tube is not inside the expiratory tube. Anadvantage of unilimb breathing tubes is that exhaled gases flow aroundthe inspiratory tube warming the gases therein, which aids inmaintaining the patient's temperature at a comfortable level. Aheat-moisture-exchanger (“HME”) can be placed between the unilimbbreathing tube and the gas delivery device to warm and moisturize theinhaled gases. The HME may comprise layers of foam and paper impregnatedwith hygroscopic salts.

Unilimb breathing tubes may comprise drapable and/or collapsible tubing.Drapable tubing comprises corrugations that are not collapsible.Collapsible tubing can, advantageously, be longitudinally collapsed toreduce the length of the coaxial breathing tube for storage andtransportation, while enabling longitudinal expansion when the unilimbbreathing tube is used. Longitudinal expansion can be controlled toprovide a desired length. An example unilimb breathing tube is describedin commonly owned U.S. Pat. No. 7,178,521, titled “Adjustable LengthBreathing Circuit,” issued on Feb. 20, 2007, which is incorporatedherein by reference.

A breathing circuit system may include a filter device. The filterdevice may be located between the unilimb breathing tube and the gasdelivery device or between the unilimb breathing tube and theventilator. If the filter device is positioned between the unilimbbreathing tube and the gas delivery device, the unilimb breathing tubemay be protected from contamination and, possibly, reused. If the filterdevice is positioned between the unilimb breathing tube and theventilator, at least the expiratory tube should not be reused becauseexpired gases may contaminate it. In both instances the filter devicemay prevent contamination of the ventilator if the filter is interposedin the expiratory path of the breathing circuit. Of course filterdevices may be located at both ends of the unilimb breathing tube.However it is preferable to position filter devices at the machine endto reduce clutter near the patient.

An embodiment of a filter device 50 will now be described with referenceto FIGS. 3, 4 and 5 . Filter device 50 includes a distal housing 52coupled to a proximal housing 54. Distal housing 52 includes aninspiratory chamber wall 56, an expiratory chamber wall 60, an innerport 58, and an outer port 62. Distal housing 52 also includes aperipheral wall 64, and a medial wall 92 extending between inspiratorychamber wall 56 and expiratory chamber wall 60. Medial wall 92 ends inwalls 94, 98 defining a transverse groove 96 between them (best shown inFIG. 5 ). Inspiratory chamber wall 56 together with medial wall 92 forman inspiratory chamber 86. Inspiratory chamber wall 56 extends to forman inner wall 68 opposite peripheral wall 64 and forming a groove 66therebetween. Expiratory chamber wall 60 together with medial wall 92form an expiratory chamber 90. Expiratory chamber wall 60 extends toform an inner wall 70 opposite peripheral wall 64 and forming a groove72 therebetween. A filter 100 and a filter 102 are sealingly affixed tofilter device 50.

Proximal housing 54 includes an inspiratory chamber wall 76, anexpiratory chamber wall 80, an inner port 78, an outer port 82, and amedial wall 88. Inspiratory chamber wall 76 together with medial wall 88form an inspiratory chamber 87. Expiratory chamber wall 80 together withmedial wall 88 form an expiratory chamber 91. Proximal housing 54 alsoincludes a tongue 84, extending from inspiratory chamber wall 76,expiratory chamber wall 80, and medial wall 88, which forms a tongue andgroove joint with grooves 66, 72, and 96 when proximal housing 54 isaffixed to distal housing 52, thereby sealing inspiratory chambers 86and 87 and expiratory chambers 90 and 91. Inspiratory chamber wall 76extends to form an inner wall 69 opposite tongue 84. The edge of filter100 is affixed between inner wall 68 and inner wall 69. The edge offilter 102 is affixed between inner wall 70 and an inner wall 71extending from expiratory chamber wall 80, thereby preventing gas flowexcept through the filters. Substantially all the gases flowing from theventilator to the patient pass through filter 100 and substantially allthe gases flowing from the patient to the ventilator pass through filter102 when the filter device, the unilimb breathing circuit, and thedelivery device are connected properly. When filter device 50 isintegrated with unilimb breathing circuit 20, all the gases entering orleaving filter device 50 from/to the ventilator pass through filter 100or filter 102. When filter device 50 is integrated with unilimbbreathing circuit 20, all the gases entering or leaving filter device 50from/to the ventilator pass through filter 100 or filter 102 and thedistal connector of unilimb breathing circuit 20.

Medial walls 88 and 92 divide filter device 50 such that filters 100 and102 are substantially equal in surface area. In other embodiments, thechamber sizes can be adapted so that filters 100 and 102 are not equalin size. The filters can comprise the same or different filtering media.It may be desirable, for example, to provide a finer inspiratory filterto protect the patient and a less fine filter to protect the ventilator,in which case a larger surface area may be provided for the inspiratoryfilter to reduce the pressure across it. On the other hand a less fineinspiratory filter may be provided if there is another filter ininspiratory pathway 30. A person of skill in the art would be able tochange the volumes of the chambers to achieve a desired pressuredifferential across the filters based on the chosen filter medium anddesired filtration capability. Importantly, by providing only twochambers in each housing, in contrast with prior art filter deviceswhich have four chambers in each housing, laminar flow is improved whichreduces resistance to flow. Furthermore, mating of the housings withtongue and groove joints seals the chambers preventing leakage betweenpathways and to the environment, regardless of pressure.

In some embodiments, filter 102 is omitted and the expiratory chambersare reduced in size to reduce the overall size of filter device 50. Insome embodiments, filter 100 is omitted and the inspiratory chambers arereduced in size to reduce the overall size of filter device 50.

Another embodiment of a filter device, denoted by numeral 120, will nowbe described with reference to FIG. 6 . Filter device 120 is similar tofilter device 50, except that proximal housing 54 is modified toincorporate the function of a manifold. Filter device 120 includesdistal housing 52 coupled to a proximal housing 122. Proximal housing122 includes inspiratory chamber wall 76, an expiratory chamber wall130, inner port 78, and an outer port 132 extending from an expiratorytube 134 connected to expiratory chamber wall 130. Distal ports 58, 62are co-axial. By using filter device 120 a user avoids the need for aseparate manifold, reducing cost and space requirements. In a variationof the present embodiment, filter device 120 is further modified toinclude the ultrasonic bonding features described with reference toFIGS. 9 and 10 .

In the embodiments described with reference to FIGS. 3 to 6 , the filterdevice is separable from the breathing tube. The breathing tube can be aunilimb tube or a dual limb tube. The filter device is connected to aproximal connector of the breathing tube to form the breathing circuit.FIGS. 7 and 8 illustrate breathing circuit devices incorporating filterdevices 50, 120. FIG. 7 shows manifold 18 interposed between ventilator12 and filter device 50. By contrast, FIG. 8 shows that manifold 18 hasbeen omitted and ventilator 12 is directly connected to filter device120. Unilimb breathing circuit 22 is sealingly bonded with filterdevices 50, 120 further reducing the likelihood of leakage. The bond maybe formed by ultrasonic or adhesive bonding, for example. Of courseunilimb breathing circuit 22 may be substituted, in some embodiments,with other breathing tubes known in the art, including dual limb tubesand unilimb tubes in which the diameter of the tube is bifurcated by amembrane to form two lumens therein.

FIGS. 9 and 10 illustrate another embodiment of a filter device, denotedby numeral 50′. Filter device 50′ includes features which facilitateultrasonic bonding of a distal housing 52′ to a proximal housing 54′. Inall other respects distal housing 52 and proximal housing 54 areidentical to distal housing 52′ and proximal housing 54′. Proximalhousing 54′ is provided with a collar extending from tongue 66. From thecollar a protrusion 140 extends parallel to tongue 84. Protrusion 140 isconfigured to fit into a groove 142 disposed on distal housing 52′.During construction, after filter device 50′ is assembled, ultrasonicenergy can be directed to protrusion 140 to ultrasonically bondprotrusion 140 and groove 142. In the present embodiment, the tongue andgroove joint described with reference with FIG. 50 facilitates assemblyby insertion of the tongue into the groove, and creates a press-fitseal, and then the ultrasonic bond provides a fluid seal. Thecombination of the tongue and groove joint and the fluid seal provides arobust seal between the housings.

In the embodiments described above the tongue is provided in theproximal housing and the groove is provided in the distal housing. Inother embodiments the tongue is provided in the distal housing and thegroove is provided in the proximal housing.

An embodiment of a test plug 150 will now be described with reference toFIGS. 11, 12, and 13 . Test plug 150 comprises an inner port plug 152and an outer port plug 154. Inner port plug 152 is inserted in an innerport 162 of a distal end connector 160 of a breathing tube to test forleakage in the inspiratory pathway during the leakage test. Thebreathing tube may comprise breathing tube 22 having distal connector160. FIG. 12 illustrates inner port plug 152 inserted in inner port 162.FIG. 13 illustrates outer port plug 154 inserted in an outer port 164 ofdistal end connector 160 to test for leakage in the expiratory pathway.The external circumferences of inner port plug 152 and outer port plug154 are slightly tapered and configured to press-fit into ports 162, 164of proximal end connector 160. During the test, the breathing tube isfluidly coupled to the ventilator. The ventilator pressurizes theinspiratory pathway to the test it, with the distal end of theinspiratory pathway plugged by inner port plug 152. The ventilatorpressurizes the expiratory pathway to the test it, with the distal endof the expiratory pathway plugged by outer port plug 154. In a similarmanner the ventilator may test the filter device.

Tighter seals, lower tidal volumes, and more recycling of expired gasesreduce the amount of moisture that may escape or be removed from theunilimb breathing tube. Accordingly, increased amounts of moisture canaccumulate. Furthermore, it is desirable to keep moisture from enteringthe ventilator. Below are described various embodiments, described withreference to FIGS. 14 to 16 comprising absorbent features to trapmoisture. These features may be incorporated in the breathing tube, forexample breathing tube 22, or in the filter device, for example filterdevice 50, 50′, and 120.

In some embodiments, absorbent material is provided in the expiratorypathway to absorb moisture. In one example the absorbent materialcomprises superabsorbent gel. In one example, shown in FIG. 14 , atubular insert 174 is disposed between the inner tube 32 and the outertube 34 of a unilimb breathing tube 170, the tubular insert comprisingthe absorbent material 172. The absorbent material may also be extrudedin a layer of a coextruded expiratory and/or inspiratory tube, orlaminated or impregnated instead. FIG. 15 shows absorbent material 172extruded in an internal layer of external tube 34 of a unilimb breathingtube 176. FIG. 16 shows absorbent material 172 extruded in an externallayer of inner tube 32 of a unilimb breathing tube 180. The absorbentmaterial may also be provided in a breathable packet disposed in theexpiratory pathway. In one variation, the absorbent material is providedin the filter device described above, for example in the proximal ordistal expiratory chambers. Therefore, the filter device accumulates themoisture. The absorbent material may also be incorporated with filter102.

In some embodiments, the inspiratory tube comprises a moisture permeablemembrane. The moisture permeable membrane enables passage of moisturefrom the expiratory pathway to the inspiratory pathway. The membrane maybe located near the proximal end of the unilimb breathing tube. Passageof the moisture to the inspiratory tube reduces moisture in theexpiratory tube and also humidifies the inspiratory pathway gases, whichis beneficial for the patient. The moisture also transfers heat, therebyheating the inspiratory pathway gases.

An inspiratory tubular extension may be provided which comprises themoisture permeable membrane in order to reduce manufacturing complexity.The extension may be coupled to the inspiratory tube on one end and tothe distal inner port of the filter device or the manifold on the otherend. In another example, the moisture permeable membrane comprises amonolithic membrane configured to draw moisture via diffusion. Anabsorbent material may be provided on one side of the monolithicmembrane to provide the moisture, which is then diffused to theinspiratory pathway where it is absorbed by the inspiratory pathwaygases. Monolithic membranes can comprise, for example, a hydrophilicpolyether block amide, which is waterproof while also exhibiting highpermeability to moisture vapor. Microporous membranes may also be used.Microporous membranes may comprise, for example, solid particles in apolymer film. Tortuous paths are then formed between the particles bystretching the polymer film. Calcium carbonate is a known solid particleused to make polymeric films. A sulfonated tetrafluoroethylene basedfluoropolymer-copolymer membrane may also be used.

In some embodiments, a phase change material is provided. Uponactivation of the phase change material, it generates heat to warm theinspiratory pathway gases provided to the patient. Activation may occur,for example, by breaking a package to expose the phase change materialto oxygen and generate an exothermic reaction.

In some embodiments, a heating wire is provided to heat the inspiratorytube and thereby heat the inspiratory pathway gases provided to thepatient. The heating wire may be disposed in a wall of the inspiratorytube. The heating wire is connected to an electrical energy source, andit heats up due to its electrical resistance.

In some embodiments, a swivel connector is provided. The swivelconnector comprises a swivel mechanism which can rotate an element withdual ports, one port being longitudinally aligned with the distalconnector of the unilimb breathing tube (e.g. straight) and the otherport being offset by 90 degrees. The swivel connector can thus beconnected to a face mask, for example, using the offset port, and toanother gas delivery device with the straight port. The connector mayalso comprise two openings, one connected to the straight port and theother to the offset port, and rotating the connector thus connects oneor the other port via one or the other openings.

In some embodiments, an integrated circuit 192 (shown in FIG. 17 ) isprovided at or near the distal end of the unilimb breathing tube.Integrated circuit 192 may be connected to distal connector 160, 190 ofthe unilimb breathing tube of breathing tube 22. A sensing device 194may be connected to integrated circuit 192. The sensing device may befluidly coupled to the distal connector, the swivel connector or the gasdelivery device to detect a parameter associated with the inspiratorygases. Integrated circuit 192 may include a wireless transmitterconfigured to transmit a value of the parameter. In one example, theparameter value is transmitted wirelessly to the ventilator, and theventilator can thus control or adjust the anaesthetic drug volume, thepressure of the inspiratory gases, the temperature of the inspiratorygases, carbon dioxide concentration of expired gases, and any otherparameter based on the transmitted parameter value. Advantageously,transmission of parameter values reduces the number of tubes by, forexample, eliminating the need to connect a gas sampling tube to thebreathing circuit. Furthermore, measurements obtained near the patientare more beneficial than those obtained remotely, due to time anddistance induced variation. The sensor may sense, for example,anaesthetic drug concentration, flow rate, pressure, presence ofbacteria, temperature, pressure, movement, etc. Any sensor known in theart may be used.

Integrated circuit 192 may comprise a system-on-a-chip with a processor,analog-to-digital converter, and a wireless transmitter configured totransmit the digital data. The sensor may comprise, for example, anaccelerometer or gyroscope to measure motion. The sensor may alsomeasure colors to detect a chemical reaction resulting from the presenceof bacteria. A bacteriocidal threshold may be provided to indicatewhether the unilimb breathing tube may be reused. If the value is abovethe threshold, the device must be discarded. The integrated circuit mayalso provide an alarm signal if the sensed parameter value is outside asafe range. For example, excessive movement may be indicative of patientdistress. A discontinuity in flow may be indicative of a disconnectionin the breathing circuit or a failure of the ventilator. A wirelessreceiver may be incorporated in the ventilator or provided in a separatemonitoring device, for example in a portable monitoring device usableduring transportation of the patient or in the field.

Below are disclosed additional examples of breathing circuit devices.

In an example A, a breathing circuit device comprises an expiratory tubeproviding an expiratory pathway for expired gases from a patient; aninspiratory tube inside the expiratory tube, the inspiratory tubeproviding an inspiratory pathway for inspired gases to be provided tothe patient; a distal connector connected to the expiratory tube and tothe inspiratory tube; a proximal connector connected to the expiratorytube and to the inspiratory tube; and an absorbent material configuredto absorb moisture from the expired gases, the absorbent materialpositioned between the distal connector and the proximal connector.

A breathing circuit device as in example A, wherein the absorbentmaterial comprises a superabsorbent polymer. In one variation, theexpiratory tube comprises an external layer and an internal layer, andthe absorbent material is supported by the internal layer.

A breathing circuit device as in example A, further comprising a tubularsleeve having a diameter larger than the inspiratory tube and smallerthan the expiratory tube, the inspiratory tube passing through thetubular sleeve and comprising the absorbent material.

A breathing circuit device as in example A, wherein the absorbentmaterial is attached to an external surface of the inspiratory tube. Inone variation, the absorbent material is laminated to the externalsurface of the inspiratory tube.

A breathing circuit device as in example A, further comprising a filterdevice including a distal inner port, a proximal inspiratory port, aninspiratory pathway between the distal inspiratory port and the proximalinspiratory port, a distal expiratory port, a proximal expiratory port,an expiratory pathway between the distal expiratory port and theproximal expiratory port, and at least one filter substrate in at leastone of the inspiratory pathway and the expiratory pathway. In onevariation, the filter device includes a distal housing having a distalinspiratory chamber fluidly coupled to the distal inspiratory port, anda distal expiratory chamber fluidly coupled to the distal expiratory;and a proximal housing attached to the distal housing and having aproximal inspiratory chamber coupled to the proximal inspiratory port,and a proximal expiratory chamber fluidly coupled to the proximalexpiratory port, wherein the distal inspiratory chamber is sealinglyattached to the proximal inspiratory chamber forming a sealedinspiratory pathway between the distal inspiratory port and the proximalinspiratory port, and the distal expiratory chamber is sealinglyattached to the proximal expiratory chamber forming a sealed expiratorypathway between the distal expiratory port and the proximal expiratoryport.

In one variation, the proximal housing comprises a proximal filterconnector comprising the proximal inspiratory port and the proximalexpiratory port, wherein the proximal filter connector is removablyattachable to the distal connector.

In another variation, wherein the distal inspiratory port and the distalexpiratory port of the distal housing comprise the distal connector, theproximal inspiratory port is permanently connected to the inspiratorytube, and the proximal expiratory port is permanently connected to theexpiratory tube.

In a further variation, the at least one filter substrate comprises afirst filter substrate in the inspiratory pathway and a second filtersubstrate in the expiratory pathway.

In yet another variation, the breathing circuit device further comprisesa structural sealing arrangement sealingly connecting the distalinspiratory chamber and the proximal inspiratory chamber, the structuralsealing arrangement comprising a wall inserted into a slot, the slotformed in one of the distal housing and the proximal housing, and thewall formed in the other of the distal housing and the proximal housing.

In an example B, a dual-chamber filter device comprises a distal housinghaving an inspiratory chamber and an expiratory chamber; a proximalhousing having an inspiratory chamber and an expiratory chamber; aninspiratory filter between the inspiratory chamber of the distal housingand the inspiratory chamber of the proximal housing; wherein the distalhousing and the proximal housing are attached, and wherein aninspiratory chamber structural sealing arrangement sealingly couples theproximal and distal inspiratory chambers to form a sealed inspiratorychamber and an expiratory chamber structural sealing arrangementsealingly couples the distal and proximal expiratory chambers to form asealed expiratory chamber.

A dual-chamber filter device as in example B, wherein the expiratorychamber structural sealing arrangement comprises a slot surrounding theexpiratory chamber and a wall or ledge inserted in the slot to seal theexpiratory chamber.

A dual-chamber filter device as in example B, further comprising adistal inspiratory port, a distal expiratory port offset by more than 30degrees from the distal inspiratory port, a proximal inspiratory port,and a proximal expiratory port, wherein the proximal inspiratory portand the proximal expiratory port are substantially coaxial.

A dual-chamber filter device as in example B, further comprising adistal inspiratory port, a distal expiratory port offset by about 90degrees from the distal inspiratory port, a proximal inspiratory port,and a proximal expiratory port, wherein the proximal inspiratory portand the proximal expiratory port are substantially coaxial.

In an example C, a breathing tube comprising an inner tube fluidlycoupled to the distal inner port; an outer tube fluidly coupled to thedistal outer port, wherein the inner tube is positioned inside the outertube; and a distal connector connecting a distal end of the inner tubeto a distal end of the outer tube.

The breathing tube of example C, wherein the inner tube and the outertube are permanently affixed to the filter device, further comprising awireless transmitter in the distal connector of the breathing circuitdevice. In a variation thereof, further comprising a sensor configuredto detect a characteristic of a gas flowing through the distalconnector, wherein the wireless transmitter is configured to transmit avalue of the characteristic of the gas.

The breathing tube of example C, further comprising a wirelesstransmitter in the distal connector of the breathing circuit device. Ina variation thereof, further comprising a sensor configured to detect acharacteristic of a gas flowing through the distal connector, whereinthe wireless transmitter is configured to transmit a value of thecharacteristic of the gas.

In an example D, a breathing tube comprising an inner tube fluidlycoupled to the distal inner port; an outer tube fluidly coupled to thedistal outer port, wherein the inner tube is positioned inside the outertube; and a distal connector (160) connecting a distal end of the innertube to a distal end of the outer tube; further comprising an absorbentmaterial positioned between the inner tube and the outer tube.

The breathing tube of example D, wherein the absorbent materialcomprises a superabsorbent polymer.

The breathing tube of example D, wherein the outer tube comprises anexternal layer and an internal layer, and the absorbent material isattached to the internal layer.

The breathing tube of example D, wherein the absorbent material isattached to an external surface of the inner tube.

The breathing tube of example D, wherein the absorbent material islaminated to the external surface of the inner tube.

The breathing tube of example D, further comprising a tubular sleevecomprising the absorbent material, wherein the tubular sleeve ispositioned intermediate the inner tube and the outer tube, with theinner tube passing through the tubular sleeve.

The breathing tube of example D, wherein the inner tube and the outertube are permanently affixed to the filter device, further comprising awireless transmitter in the distal connector of the breathing circuitdevice. In a variation thereof, further comprising a sensor configuredto detect a characteristic of a gas flowing through the distalconnector, wherein the wireless transmitter is configured to transmit avalue of the characteristic of the gas.

The breathing tube of example D, further comprising a wirelesstransmitter in the distal connector of the breathing circuit device. Ina variation thereof, further comprising a sensor configured to detect acharacteristic of a gas flowing through the distal connector, whereinthe wireless transmitter is configured to transmit a value of thecharacteristic of the gas.

While the invention has been described as having exemplary designs, thepresent disclosure may be further modified within the spirit and scopeof this disclosure. This application is therefore intended to cover anyvariations, uses, or adaptations of the disclosure using its generalprinciples. Furthermore, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains.

What is claimed is:
 1. A breathing circuit system, comprising: a filterdevice including: a distal housing comprising a first distal chamberwall and a second distal chamber wall, a distal medial wall extendingbetween the first distal chamber wall and the second distal chamberwall, a distal inner port and a distal outer port; a proximal housingcomprising a first proximal chamber wall and a second proximal chamberwall, a proximal medial wall extending between the first proximalchamber wall and the second proximal chamber wall, a proximal inner tubehaving a longitudinal axis and a proximal opening forming a proximalinner port, a proximal outer tube having a longitudinal axis and anopening forming a proximal outer port, the longitudinal axis of theproximal outer tube extending laterally relative to the longitudinalaxis of the proximal inner tube at an angle of between 60 and 100degrees, and the proximal housing being affixed to the distal housing toform an inspiratory pathway and an expiratory pathway fluidly sealedfrom the inspiratory pathway; and a first filter in the inspiratorypathway or in the expiratory pathway, to filter gases flowing throughthe inspiratory pathway or the expiratory pathway.
 2. The breathingcircuit system of claim 1, the distal housing further comprising adistal inner tube having a distal opening forming the distal inner port;and a distal outer tube defining a lumen and having a distal openingforming the distal outer port, wherein at least a portion of the distalinner tube is positioned in the lumen of the distal outer tube.
 3. Thebreathing circuit system of claim 2, wherein the distal inner tube andthe distal outer tube are coaxial.
 4. The breathing circuit system ofclaim 1, wherein the proximal inner tube extends from the first proximalchamber wall and the proximal outer tube extends from the secondproximal chamber wall.
 5. The breathing circuit system of claim 1,further comprising a test plug including an expiratory pathway plughaving a substantially cylindrical wall with an outer surface sized andshaped to plug the expiratory pathway to enable leak-testing of theexpiratory pathway, the substantially cylindrical wall having an openend and a closed end opposite the open end.
 6. The breathing circuitsystem of claim 5, wherein test plug comprises an inspiratory pathwayplug having an outer surface sized and shaped to plug the inspiratorypathway to enable leak-testing of the inspiratory pathway.
 7. Thebreathing circuit system of claim 6, wherein a diameter of the outersurface of the inspiratory pathway plug tapers longitudinally to enablepositioning of the inspiratory pathway plug at least partly into acylindrical tube of the inspiratory pathway, and wherein a diameter ofthe outer surface of the expiratory pathway plug tapers longitudinallyto enable positioning of the expiratory pathway plug at least partlyinto a cylindrical tube of the expiratory pathway.
 8. The breathingcircuit system of claim 6, wherein the test plug comprises asingle-piece part including the expiratory pathway plug and theinspiratory pathway plug.
 9. The breathing circuit system of claim 6,further comprising an inner tube having a proximal end fluidly coupledto the distal inner port, wherein the inspiratory pathway extendsthrough the inner tube; an outer tube having a proximal end fluidlycoupled to the distal outer port, wherein the expiratory pathway extendsthrough the outer tube; and a distal connector having an outer tubeconnected to a distal end of the outer tube and an inner tube connectedto a distal end of the inner tube, the distal connector having acylindrical gap between the outer tube and the inner tube, wherein theouter surface of the expiratory pathway plug is sized and shaped to fitinto and fluidly seal the outer tube of the distal connector, andwherein the outer surface of the inspiratory pathway plug is sized andshaped to fit into and fluidly seal the inner tube of the distalconnector.
 10. The breathing circuit system of claim 9, wherein thesubstantially cylindrical wall of the expiratory pathway plug is sizedand shaped to fit in the gap.
 11. The breathing system device of claim1, wherein the proximal outer tube of the filter device extends furtherlaterally from the proximal housing relative to the proximal medial wallthan the second proximal chamber wall.
 12. The breathing circuit systemof claim 1, further comprising a tongue and groove joint comprising agroove formed in the distal housing or the proximal housing and a tongueformed in the other of the distal housing or the proximal housing, thetongue and groove joint forming a first fluid seal between theexpiratory pathway and the inspiratory pathway from each other and fromthe external environment.
 13. The breathing circuit system of claim 12,further comprising a circumferential protrusion formed in the distalhousing or the proximal housing and a circumferential groove formed inthe other of the distal housing or the proximal housing, thecircumferential protrusion configured to fit in the circumferentialgroove during assembly.
 14. The breathing circuit system of claim 13,wherein the circumferential protrusion and the circumferential grooveare disposed outwardly of the tongue and groove joint and form a secondfluid seal.
 15. A method of testing a breathing circuit, comprising:providing a breathing circuit including a filter device comprising adistal housing comprising a first distal chamber wall and a seconddistal chamber wall, a distal medial wall extending between the firstdistal chamber wall and the second distal chamber wall, a distal innerport and a distal outer port; a proximal housing comprising a firstproximal chamber wall and a second proximal chamber wall, a proximalmedial wall extending between the first proximal chamber wall and thesecond proximal chamber wall, a proximal inner tube having alongitudinal axis and a proximal opening forming a proximal inner port,a proximal outer tube having a longitudinal axis and an opening forminga proximal outer port, and the proximal housing being affixed to thedistal housing to form an inspiratory pathway and an expiratory pathwayfluidly sealed from the inspiratory pathway; and a first filter in theinspiratory pathway or in the expiratory pathway, to filter gasesflowing through the inspiratory pathway or the expiratory pathway;fluidly sealing the inspiratory pathway with an inspiratory pathway plugof a test plug; pressurizing the inspiratory pathway; monitoring apressure in the pressurized inspiratory pathway to detect a leak;fluidly sealing the expiratory pathway with an expiratory pathway plugof the test plug; pressurizing the expiratory pathway; and monitoring apressure in the pressurized expiratory pathway to detect a leak.
 16. Themethod of claim 15, wherein pressurizing of the inspiratory pathwayoccurs prior to or after pressurizing of the expiratory pathway.
 17. Themethod of claim 15, wherein, wherein the longitudinal axis of theproximal outer tube of the filter device extends laterally relative tothe longitudinal axis of the proximal inner tube at an angle of between60 and 100 degrees.
 18. The method of claim 15, wherein the inspiratorypathway plug and the expiratory pathway plug are positioned at oppositeends of the test plug.
 19. The method of claim 15, wherein fluidlysealing the inspiratory pathway comprises press-fitting the inspiratorypathway plug into an inner tube of a distal connector of a unilimbcircuit.
 20. The method of claim 19, wherein fluidly sealing theexpiratory pathway comprises press-fitting the expiratory pathway pluginto an outer tube of the distal connector of the unilimb circuit.
 21. Atest plug for testing a breathing circuit system, comprising: anexpiratory pathway plug having a substantially cylindrical wall with anouter surface sized and shaped to plug an expiratory pathway and therebyenable leak-testing of the expiratory pathway, the substantiallycylindrical wall having an open end and a closed end opposite the openend; and an inspiratory pathway plug having an outer surface sized andshaped to plug an inspiratory pathway and thereby enable leak-testing ofthe inspiratory pathway.
 22. The test plug of claim 21, wherein thesubstantially cylindrical wall has a cylindrical inner surface with adiameter larger than the outer surface of the inspiratory pathway plug.23. The apparatus of claim 22, wherein the inspiratory pathway plug andthe expiratory pathway plug extend from opposite ends of the test plug.